1. Field of the Invention
The present invention relates to nuts for use in securing various elements to cooperating bolts or screws, and more particularly pertains to a new and improved nut for use on roadways adapted to minimize damage to vehicle tires and shocks to vehicle suspensions, as well as providing an increased service life.
2. Description of the Prior Art
Various types of nuts are known in the prior art. A typical example of such a nut is to be found in U.S. Pat. No. 800,189, which issued to D. Ward on Sep. 26, 1905. This patent discloses a generally rectangular nut with a concave curvature, formed from a spring metal plate and having a substantially rectangular central aperture with four partially screw threaded sides to present eight locking corners. U.S. Pat. No. 1,865,346, which issued to W. Wells on Jun. 28, 1932, discloses a generally triangular nut having a central threaded aperture and a semi-cylindrical recess formed at each apex. The apex recesses are adapted to engage jaws of a complementary wrench for purposes of tightening the nut. Additionally, this patent discloses that the apex recesses may be employed to receive therethrough a pin screw or other similar fastener anchored in a stationary structure which will lock the nut against retrograde movement. U.S. Pat. No. 1,882,462, which issued to S. Weber on Oct. 11, 1932, discloses a spanner wrench having a plurality of pin-type adjustable jaws for engagement with apertures, notches or recesses in a nut for purposes of driving the same. U.S. Pat. No. 1,937,109, which issued to S. Colt on Nov. 28, 1933, discloses a nut structure for retaining a concrete pouring form which employs a central circular aperture for engagement with a threaded stud and peripheral apertures for engagement with securing nails or pins. U.S. Pat. No. 2,284,824, which issued to D. Hungerford on Jun. 2, 1942, discloses an anchor nut having a central threaded circular aperture and radially outer, diametrically opposed, reduced diameter smooth bore apertures. U.S. Pat. No. 2,556,672, which issued to R. Bergh et al on Jun. 12, 1951, discloses a nut having a central threaded aperture surrounded by a radial flange through which reduced diameter bores are positioned. The reduced diameter bores are adapted for use with locking wires to prevent backing off of the nut. U.S. Pat. No. 2,591,631, which issued to W. Stanitski on Apr. 1, 1952, discloses a nut for use in securing a vehicle wheel including a central threaded aperture surrounded by a plurality of evenly spaced radially outer smaller diameter apertures adapted to receive locking wires for preventing backing off of the nut after installation. U.S. Pat. No. 3,796,123, which issued to W. Duffy et al on Mar. 12, 1974, discloses a sheet metal nut having an inner threaded barrel portion connected to an outer, hexagonally shaped barrel portion by a connecting web adjacent one end and including a hexagonally-shaped depression formed in the inner barrel portion over a limited axial extent. The internal phases of the hexagonal depression are disposed opposite to and match the hex wrenching faces on the outer barrel portion and are effective to transmit torque to the inner barrel portion when the nut is turned onto a mating bolt thereby reducing torsional strain on the connecting web incident to tightening of the nut. U.S. Pat. No. 3,821,975, which issued to L. Haker on Jul. 2, 1974, discloses an automotive wheel nut having a frustoconical periphery and an outer face including a pair of wrench receiving openings of different diameters and spaced angularly at oblique angles. A spanner type socket wrench in the shape of a nut has a clearance hole to fit over the wheel stud which projects from the nut and pins in its inner face so spaced to engage the openings in the nut. A conventional driver may be utilized for rotating the wrench to tighten or loosen the wheel nut. The device is intended for use as an anti-theft vehicle wheel lock. U.S. Pat. No. 4,269,248, which issued to B. MacLean et al on May 26, 1981, discloses a threaded nut including a body portion with a bearing surface at a workpiece engaging end defined by a flange. Segments of the bearing surface defined by the flange are flexible and resilient so that upon tightening of the fastener against the workpiece or other element, deflection of the resilient segment provides a spring action to compensate for developed looseness or loss of tension. Other segments of the bearing surface adjacent the flexible segments are rendered rigid by the body portion of the fastener and by brace structure associated with the body portion such that substantial spring forces are achieved. U.S. Pat. No. 4,302,137, which issued to H. Hart on Nov. 24, 1981, discloses a theft-resistant fastener for use as a vehicle wheel lock nut including a nut or bolthead and a spanner wrench component. The nut or bolthead possesses a smooth edge surface and the spanner component includes locating pins adapted to engage cooperating bores in the nut or bolthead to rotate the nut or bolthead with the spanner component. In addition to the above described nuts, the prior art also contemplates the use of externally threaded drill guide bushings for the purpose of drilling a reduced diameter aperture coaxially with a threaded bore in a component. For example, U.S. Pat. No. 2,917,331, which issued to J. Baer et al on Dec. 15, 1959, discloses an externally threaded guide bushing having a reduced diameter internal bore and a spoke driving surface to facilitate installation of the drill guide bushing in a threaded bore. After the drill guide bushing is installed, a conventional drill is utilized to drill the reduced diameter bore in a mating component and a cylindrical pin is inserted therethrough to rotationally fix the components against relative movement. U.S. Pat. No. 386 739 which issued to J. Connelly on Jul. 24, 1888, discloses another type of externally threaded drill guide bushing having a locking nut for securing the drill guide in an adjusted position.
While the above mentioned devices are directed to various types of nuts, spanner wrenches and drill guide bushings, none of these devices discloses a nut having spherically curved upper and lower surfaces in conjunction with a central threaded aperture surrounded by a plurality of radially outer, reduced diameter, threaded apertures. Additionally, none of the aforesaid prior art devices have been found to overcome problems associated with the use of fasteners on roadway surfaces, particularly those problems associated with a short surface life due to thermal and mechanical fatigue. Further, prior art fasteners utilized on roadway surfaces have been found to cause substantial damage to tires and vehicle suspensions and as such an improved nut is desired. Inasmuch as the art is relatively crowded with respect to these various types of nuts, it can be appreciated that there is a continuing need for and interest in improvements to such nuts, and in this respect, the present invention addresses this need and interest.